


Milkbones

by GioGioStar



Category: Undertale
Genre: Begging, Crying, Dry Humping, Ecto-Penis, Ecto-Tongue, Fontcest, Incest, Lactation Kink, Loss of Virginity, M/M, Skeleton Heat, cute shaped nipples, ecto tits, humping, sex puns, star shaped nipples
Language: English
Status: Completed
Published: 2016-06-20
Updated: 2016-06-20
Packaged: 2018-07-16 03:49:02
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,284
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7250776
Author URL: https://archiveofourown.org/users/GioGioStar/pseuds/GioGioStar
Summary: <blockquote class="userstuff">
              <p>Papyrus's heat has taken to new means as it ravages his body. Can Papyrus convince his brother to give him a hand or will his heat be the death of him?</p>
            </blockquote>





	Milkbones

**Author's Note:**

> I originally posted this in Tumblr as an art trade/commission for the tumblr user bones-n-boners.
> 
> If you wish to check out some of my other work, you can go to www.giogiostar.tumblr.com

Sans stared at his little brother, chuckling at the situation he was in. Heat was a normal part in monsters lives. But he had never seen something like this before. He had heard of it, but never thought that he would live to see the day where somebody’s heat would cause a monster to grow parts their gender traditionally wouldn’t have. This was perhaps the funniest thing he had ever seen in his life. His brother went to bed last night a normal skeleton and woke up with breasts that were possibly bigger than his own head. All day he had been cracking jokes.

“SANS, PLEASE.” Papyrus was begging as he shifted uncomfortably in bed.

 

“aww, come on paps, i haven’t told you my _breast_ boob pun yet. it’s _titalizing_.”

 

The taller skeleton was losing it. He his chest had been hurting all day and his brother’s puns were not helping him. Every once in a while, he felt magic slowly leaking from his nipples. It was so uncomfortable. It was soaking his shirt and it wasn’t making his heat any easier to handle. Normally, when he was in heat, this would be the only time he would actually lay in bed and do nothing. He hated when his heat would come. It distracted him too much from being able to do his royal guard training and his sentry duties. The first time his heat came, his older brother just lazily tossed a weird item at him and said to go wild. It had so many buttons and when he figured out how to use it, in the end, he just felt so guilty. After that, he just rode out the heat. It normally would last a day or two, three if it was bad. But in all these years, he had never had his heat get to this point.

 

Sans looked at Papyrus, surprise plastered on his face. He saw his brother shaking, tears starting to well up in his eye sockets. His heat had never been this bad. This was starting to worry him.

 

“paps, awww, bro, i’m sorry.” Sans sighed as he sat down on his brother’s race car bed, rubbing his temple gently. “i didn’t know it was that bad.”

 

“IT’S NEVER HURT THIS MUCH.” Papyrus let a few tears flow from his sockets.

 

“have you been using the thing i gave you?” Sans asked as he rubbed the top of his brother’s head.

 

“NO.”

 

Sans let out a chuckle. He couldn’t understand why his brother wouldn’t use the toy he gave him years ago. Heat was a delicate thing for monsters. It threw their magic out of wack. And considering that his brother wasn’t using it and he was pretty sure his brother wasn’t involved with anybody, it made sense as to why his body was reacting like this with his heat.

 

“where does it hurt?” Sans asked sweetly.

 

“EVERYWHERE.” Papyrus sighed.

 

“next time, use the thing i gave you.”

 

“I DON’T WANT TO.” Papyrus muttered.

 

“why?”

 

“IT’S EMBARRASSING.”

 

“bro, i’d rather use that thing than wake up and get two new _identitties_.” Sans smiled at the end.

 

“OH GOD, THAT WAS A PUN.” Papyrus groaned out.

 

“okay, paps, i’m done with the puns.” Sans sighed.

 

“THANKS.”

 

Sans was looking at his brother. It hit his soul seeing his brother like this. Besides the fact that he was suffering from his lame jokes and puns, he looked like he was actually starting to be in a lot of pain. Papyrus’s breasts looked like they had grown a bit more since the beginning of the day. This didn’t look good. His breasts looked like they might burst from the built up magic.

 

A sudden idea popped into his head. If the lack of his brother not taking care of his needs was what got him to this point, then the only way to ease his discomfort was for him to take care of it. He would leave him alone for a couple of hours so he could give Papyrus some privacy if it was too embarrassing for him to touch himself if he was around.

 

“pap, maybe i should leave you alone so you can take care of this problem.” Sans used his head to point at his brother’s chest.

 

Sans stood up quickly getting ready to leave when his brother grabbed his hand. Sans turned to see his brother in tears now. His bones rattled in need as an orange glow erupted from Papyrus’s cheeks.

 

“PLEASE, HELP ME.” Papyrus let out in need.

 

“paps.” Sans sighed as he sat back down.

 

Papyrus lifted his body, the sheets fell to his lap as they revealed two large breasts. They were orange with Papyrus’s magic. The areola was a darker orange from the breasts in a delicate star shape. Sans looked in shock at the large pair his brother was sporting. He noticed a light colored fluid seeping from the nipples.

 

Sans felt a slight blush spread across his face. He didn’t know why his body was moving closer. He couldn’t stop himself even if he tried. Slowly, he got closer to one of the breasts, one of them close to his mouth while the other he could barely touch with one of his phalanges. Sans didn’t have to look up at his brother to tell that his body shivered. Sans mind was swimming. This was a new experience even for himself. Gently he let his tongue swirl around the nipple, the slightest touch made the nipple erupt with magic. Sans was shocked. It tasted almost like milk. His brother was lactating some kind of magic from his breasts.

 

Sans nibbled down on the nipple as Papyrus let out a hissed cry. Sans smiled as he was rewarded with a mouth full of milk. He was surprised by the taste. In the beginning it was a little sour, most likely because the milk that stuck to Papyrus’s nipple was old, but the new milk had a very sweet taste to it. It was almost as if it was vanilla with almonds. It tasted really good.

 

“SANS… THAT… HURTS…” he let out a moan.

 

Sans nodded apologetically as he released his teeth from the nipple. He rolled his tongue on the nipple, trying to get more of the milk out. He wasn’t getting as much milk with just his tongue compared to when he bit down. But his brother’s breasts were too sore for him to bite on them again.

 

Sans lazily continued to tease the nipple, trying to coax it into releasing more of the sweet nectar. After a few minutes of his attempts being refused, he moved on to the other breast, his tongue tracing the areola’s odd star shape on Papyrus’s breasts. Sans smiled as Papyrus let out a soft moan. The nipple soon began to leak gently the magical milk that he wanted. But like the first nipple, after a while, it would stop.

 

“paps, how do you feel?” Sans asked as he lifted his head.

 

The orange milk dripped from Sans chin as he looked at his brother. Papyrus looked at his brother with a  weak smile. His breasts were not hurting as much, but they still felt so raw. It felt like even the slightest touch felt like a hot flame licked him. He figured it was because of the sudden growth over the day more than Sans actually nibbling at them.

 

“THEY FEEL A LITTLE BETTER.” he answered carefully.

 

“i think i know how to ease them more.” Sans started, “but i’m going to have to suck on them. if you feel uncomfortable with me doing that, i’ll stop.” Sans spoke reassuringly.

 

“DO WHATEVER YOU THINK WILL HELP.” Papyrus sighed as he laid back down on his bed.

 

Sans smiled as he started massaging his brother’s mounds. Papyrus winced every once in a while due to how tender they still were. But even though he felt the pain, there was a mixture of pleasure that came with the touches. It was starting to become difficult for him to even distinguish between the two feelings. Sans bit down softly on one of the nipples as he began to suckle. His breathing relaxed as the milk slowly began to flow like a trickling stream. He felt a heavy blush cross over his face as he continued to suck on the nipple idly. It surprised Sans as Papyrus started to moan out his name. He could feel his magic begin to pool around his pelvic bone. Sans ignored it, however. This wasn’t the time for him to get aroused. He needed to concentrate on helping his brother.

 

With a loud wet pop, Sans let go of the nipple. He could feel the milk that he hadn’t swallowed drip all over his checks and chin. Slowly he began to kiss sweetly to the other breast, feeling his brother shiver with every touch. Again, he started sucking on the other breast, giving the same amount of attention to the other one. And like before, he was compensated with the sweet milk his brother was producing.

 

Papyrus felt like he was losing himself to Sans attention. His body was craving for more. He needed this. Oh god did he need this. Especially because of so many times he neglected to even indulge in his own heats for years. He felt like his body would turn to dust refused to take care of it. And now that his brother was helping him, he just wanted to dive more.

 

“I WANT…” Papyrus couldn’t finish his train of thought.

 

Oh how he wanted his brother so badly. But he felt so dirty in even saying it out loud. Papyrus let his hands roam to his own pelvis, shocked as he brushed against Sans’ pubic region. He could feel the heat coming off of his brother’s bones. His brother was starting his own heat because of him.

 

“SANS… I…” Papyrus huffed as he tried to speak. “WANT… YOU…”

 

Papyrus was losing control of his body as he felt his hips grind against his brother. Sans chocked on the milk from the sudden pressure. Papyrus was driving him over the edge. Sans already knew that he was in too deep at this point to stop whatever was going to happen. He could feel his hips move at the same tempo as his brother’s. Milk began to dribble out of Sans mouth as he let out a low moan. As Sans began rubbing his hips on his brother’s, he began to grab at the still swollen breasts.

 

Papyrus, while grinding, let out a cry as Sans began to attack his breasts. Milk shot out suddenly in the middle of Sans squeezing his breasts. Sans smiled as he squeezed again, trying to aim the stream towards his mouth. Papyrus groaned at Sans’ actions.

 

“oh my god, bro. your tits can be used as water guns.” Sans laughed.

 

“OH MY GOD SANS!” Papyrus cried out.

 

Sans laughed as he clanked his teeth at his brother’s. He laughed out an apology as he promised that he would take this more seriously. Sans knew that this was probably going to be his brother’s first time if it did get that far. And he figured that Papyrus didn’t want it to be treated as a giant joke.

 

“okay, pap, i’m sorry.” Sans sighed as he continued to grind harder on Papyrus. “i want to make sure that you are ready for this. at any moment you change your mind, let me know and i’ll stop.” Sans kissed one of Papyrus’s star shaped nipples.

 

“I TRUST YOU, SANS. YOU’RE MY BROTHER.” Papyrus smiled as he yanked Sans by his shirt for a kiss.

 

Tongues clashed as their magic began to mix. Sans wasn’t sure who was more nervous at this point, him, or Papyrus. This wasn’t Sans first time with sex. But he knew that this was going to be Papyrus’s first time. It was scary. He was going to to take his brother’s virginity. For Sans, knowing that this was the case, it made him nervous. He wanted his brother to have his first time to be as nice as possible. He felt silly that his brother was going to lose his virginity in a race car bed.

 

Papyrus pulled down his pajama bottoms to reveal that he had already manifested female genitalia. Sans gulped as he lowered his shorts to reveal his erect member. With shaky hands, Sans grabbed Papyrus’s thighs, which developed the same ecto-skin as his breasts and slits. He could see that during the entire time they were teasing each other that Papyrus was just as aroused as he was the ecto parts glistened with wetness.

  
Sans pressed the tip of his penis at Paps entrance, a sudden shiver went down his spin. Papyrus felt so hot to the touch. Papyrus sighed as Sans pressed gingerly into him. It felt weird for Papyrus once Sans was completely inside him. It wasn’t uncomfortable, exactly. It was just a new experience that he didn’t know how to respond. Sans slowly began to thrust, a slight moan escaped through his teeth. Slowly, as Papyrus got accustomed to the pressure began to feel a tingling sensation. It was nice. He felt shock waves of pleasure flow through his body with every thrust Sans made. He could feel his hips gyrate in rhythm with Sans.

 

Sans placed his mouth on one of Papyrus’s breasts as he began to suckle in hunger as he continued to thrust. Both breasts released the sweet milk in a steady stream with the pleasure Papyrus felt. Papyrus wrapped his arms around his brother as Sans continued to pump into him. He was looking into Sans face. He had a calm expression, almost as if he was in an other world. Sans had his eyes closed softly as he suckled on the teat while he continued to thrust gently on Papyrus. It warmed Papyrus to see his brother looking relaxed.

 

Sans could feel his mouth over flow with milk as he continued to play with the large breasts. It was almost as if they were a never ending milk jug full of warmth. The milk that continued to flow was almost intoxicating. Sans felt like he was now in the land of milk and honey, and that land was the large mounds of Papyrus.

 

Sans pulled out suddenly as he unwillingly took the nipple out of his mouth. Papyrus let out a whimper before Sans motioned for Papyrus to position himself with his leg over Sans own shoulder. Again, Sans thrust into Papyrus. This new position brought on a new set of feelings. He could tell that this new position was a little deeper than the first one. Papyrus let out low moans as he saw that his breasts continued to leak steadily. Without thinking, Papyrus put a phalange in Sans mouth. Sans sucked on the finger teasingly, wrapping a tongue as he gingerly bobbed his head.

 

“SA-HANS!” Papyrus let out a moan while Sans thrust in deep.

 

Sans chuckled as he looked at Papyrus. With every thrust he made, he could see the large breasts bounce, milks sloshing which ever way they moved. Papyrus had his eye sockets closed shut as he seemed to be holding back an other moan from his body. It brought a large smile on Sans face. Papyrus just looked so sweet as he continued to pound into him. Even though they were doing this, he still held that look of innocence.

 

“you, hah, wa-hant, me to ha ha, change position?” Sans was struggling to speak as he continued to thrust.

 

“IF YOU-OOO WANT.” Papyrus moaned into his words.

 

Again, Sans pulled out quickly as he threw Papyrus’s legs over his shoulders. As soon as Sans entered Papyrus, the taller skeleton let out a cry of pure ecstasy. Sans could feel himself being sucked into deeper by Papyrus. Sans put his hands on Papyrus’s breasts as he began to grope them. The milk, to Sans surprise still flowed, lubricating the nipples as he continued to press his finger tips onto them. Papyrus let out a moan as Sans did this.

 

Sans then began to suck on the breasts, harsher than he had been doing in the beginning. It seemed that even though they were still very sensitive, they were not causing his brother pain. After a few gulps of the skelemilk, Sans held in a bit within his mouth as an idea popped into his head. While Sans had the milk in his mouth, he gave Papyrus a kiss. Milk flowed from his mouth into his brothers as Papyrus had a chocked expression. Papyrus swallowed the milk as Sans pulled away, returning to his assault on his breasts. Papyrus felt like his mind was about to implode from all the stimulation. He could feel his brother hitting his sacrum with every thrust made.

 

Papyrus took his legs off of Sans shoulders as he wrapped his legs around Sans’ waist. Sans moaned softly as he bit onto the star shaped nipple a little harder than intended. Papyrus let out a small yelp of pleasure from the love bite. This set Sans off a bit as he started to pick up a bit more speed with hos thrusts.

 

Sans grabbed Papyrus’s legs off of him as he made the taller skeleton go on all fours. The view was amazing. The ecto skin that Papyrus had made for this act was plump. He could see his slit dripping with excitement from this position. Sans just dove right in as he placed one hand on his ass and an other caressing his breast. As Sans thrust, Papyrus was crying out. He could feel his chest move in the direction of Sans pounding him. The harder Sans thrust, the more the breast moved. Papyrus was worried that he would get hit. Papyrus looked down to see that the one breast Sans had in his hand was spraying milk on the sheets. It felt nice. It was almost as if he was being milked and the heavy pressure his breasts were feeling were starting to subside.

 

Papyrus was starting to feel a new feeling from his pelvis. He wasn’t sure what it was. He had never had this feeling before. It was extremely uncomfortable. He felt like he was going to explode into a million pieces.

 

“fuck.” Sans moaned out, “i’m gonna cum soon.”

 

“WHA-? WHAT DOES THAT MEAN?” Papyrus asked as he was strangled by his own moan.

 

Papyrus could feel his body clamp down without his trying on Sans’ penis, a cry escaped from his mouth as he lost his balance. He saw that both breasts were spraying harder than when Sans was teasing.

 

Sans pulled out as he twisted his brother, laying Papyrus on his back. Sans quickly jerked his hand on his dick as he came on Papyrus’s breasts. Once the last drop fell, Sans collapsed next to Papyrus. He let out a soft chuckle as he wrapped his arm around Papryus.

 

“how ya feeling?” Sans asked as he nuzzled his head on Papyrus’s breasts.

 

“BETTER, ACTUALLY.” Papyrus sighed.

 

“well, I gotta _milk_ this one up to ya, pap, when monsters go into spells like this, it gets pretty _heated_.”

 

“SANS. TELL ME THAT YOU WEREN’T MAKING PUNS.”

 

“are you gonna _pun_ ish me if they were?”

 

“SANS NO!” Papyrus laughed as he playfully tried to push Sans off his bed.

 

“sans yes.” Sans chuckled as he clanked his teeth at Papyrus.

 

Papyrus and Sans laughed as they slowly fell asleep. Sans suckled on Papyrus as the taller skeleton rubbed the back of his head soothingly.


End file.
